Recent work has led us to the perception of the enzymes of detoxication as a coherent group of about thirty or so catalytic activities with specific features in common. Primarily, these enzymes generally have a broad spectrum of substrates with specificity for a functional group rather than for the carbon skeleton. The substrates are generally lipophilic and a usual feature is a relatively low catalytic efficiency. Emphasis in this laboratory has been on enzymes active in conjugation reactions such as those catalyzed by glutathione transferases, thiol S-methyltransferases, and steroid and phenol sulfotransferases. Work with the sulfotransferases is allowing characterization of six homogeneous enzymes active in the formation of sulfate esters of phenols, primary and secondary alcohols including hydroxysteroids, and organic hydroxylamines.